This is a great way to really support the foundation as You but,
I would rather seen the books in ebook pdf format, where you can do add-ins, that we could also pay for in the future and support the foundation.
It would be easier for you to handle bugs in the text of the books also, like Chapter 9 Application Buildding Blocks! Building with two 'd' ?
It would be nicer to have the two books on the Tablet instead. I would still be paying the full price for the books on pdf.
But. Good works of yours.